Laryngopharyngeal pH Monitoring in Patients With Idiopathic Pulmonary Fibrosis

Background: Patients with idiopathic pulmonary fibrosis (IPF) often have irritating persistent dry cough. Possible correlations between dry cough and laryngopharyngeal reflux (LPR) remain unclear. Methods: 44 patients with IPF and 30 healthy individuals underwent 24 h laryngopharyngeal pH monitoring. Ryan index score was calculated. Patients’ demographic and clinical data were collected. Results: 44 patients with IPF and 30 healthy individuals were included. The proportions of men and smokers were significantly higher in IPF group than control group (All p < 0.01). The average laryngopharyngeal pH value for 24 h was similar in the IPF (7.11 ± 0.08) group and control group (7.09 ± 0.06). According to the percentage duration of pH < 6.5, pH6.5–7.5, and pH > 7.5 in the overall measure duration, the patients were classified into three pH groups. In entire pH monitoring duration, the proportion of pH > 7.5 group in IPF patients was higher than control group; at upright position, the proportion of pH > 7.5 group in IPF patients was higher than control group; at supine position, the proportion of pH < 6.5 group in IPF patients was higher than control group (All p < 0.01). Seven patients had Ryan index score>9.41 at upright position. All patients had Ryan index score<6.79 at supine position. Four patients showed significantly higher and one patient had significantly lower average pH at coughing than the overall average pH (All p < 0.05). Conclusions: Patients with IPF may have LPR. Basic and acidic LPR may likely occur at upright and supine position, respectively. Ryan index may not accurately reflect LPR in patients with IPF.